#include <stdio.h>

int main(int argc, char *argv[]) 
{
	int min,max,sum(int n,int m);
	scanf("%d %d",&min,&max);
	printf("The sum from %d to %d is %d.\n",min,max,sum(min,max));
}
int sum(int n,int m)
{
	int sum=0;
	for(;n<=m;n++)
		sum+=n;
	return sum;
}